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WO1999035195A1 - Composition de revetement en poudre - Google Patents

Composition de revetement en poudre Download PDF

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Publication number
WO1999035195A1
WO1999035195A1 PCT/US1999/000197 US9900197W WO9935195A1 WO 1999035195 A1 WO1999035195 A1 WO 1999035195A1 US 9900197 W US9900197 W US 9900197W WO 9935195 A1 WO9935195 A1 WO 9935195A1
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WIPO (PCT)
Prior art keywords
coating
coating composition
powder
weight
composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1999/000197
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English (en)
Inventor
Michael J. Schmit
Stephen C. Hart
Wayne G. Eklund
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HB Fuller Co
Original Assignee
HB Fuller Co
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Filing date
Publication date
Application filed by HB Fuller Co filed Critical HB Fuller Co
Priority to AU21057/99A priority Critical patent/AU2105799A/en
Publication of WO1999035195A1 publication Critical patent/WO1999035195A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
    • C09D133/04—Homopolymers or copolymers of esters
    • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C09D183/04—Polysiloxanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C09D183/10—Block or graft copolymers containing polysiloxane sequences
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
    • C08L83/04—Polysiloxanes

Definitions

  • the present invention relates to a thermoforming heat-resistant powder coating composition having high heat resistance.
  • the present composition provides a coating that can be applied at high-film-build to articles. More specifically, it relates to a method wherein powder-based compositions are applied at a high-film-build and cured at temperatures greater than about 190°C or greater than about 205°C to form protective coatings which are substantially free of coating defects.
  • the present invention relates to powder-based compositions which can be applied at high film build, cured at temperatures greater than about 190°C or greater than about 205°C to form protective coatings which are substantially free of coating defects, and which display improved thermal resistance to temperatures preferably up to and above about 370°C, 425°C maneuver480°C or 540°C.
  • Powder coating compositions are well known in the established art. A variety of articles are routinely powder coated by dipping, or tumbling them in a suspended or static bed of resinous powder coating or by spray or sprinkling. The article on which the coating is applied is then heated to form a cured powder coating. These coatings have been shown to be particularly useful on metal surfaces including steel, aluminum and iron.
  • Various powder coating compositions are available that have been used in heat- resistant applications. For example, it is known in the art that aromatic epoxy resins are used to provide good heat resistance. Epoxy compositions or epoxy and silicone mixtures have also been used in the industry for the same purpose.
  • An example of a silicone coating composition is shown in U.S. Patent No. 5,433,396 (Daly et al.). However, this composition, along with the other silicone based powder coating compositions, relies on the condensation of the silicone resin with another resin or itself to form the coating composition.
  • U.S. Patent No. 4,877,837 discloses powder-based compositions comprising glycidyl functional acrylic polymers admixed with silicone having hydroxyl functional groups.
  • the compositions may contain additives such as flow agents, outgas agents and filler pigments (i.e., clay, tile, silica, hydrated silicates of aluminum and calcium metasilicate) and are cured at a temperature between 180°C - 200°C).
  • U.S. Patent No. 4,446,259 discloses coating compositions in a liquid carrier, which can be cured at ambient temperatures, comprising glycidyl functional acrylic polymers admixed with a reactive polysiloxane.
  • the coatings may contain additives such as metal oxides, metallic pigments and trace amounts of multivalent metal ions including tin and zinc.
  • Vasta also discloses fluorocarbon-based powder compositions which are baked at 200°C - 345°C for about 2 hours to provide a coating 25-75 microns thick.
  • compositions when said compositions are cured at elevated temperatures, condensation and thermal decomposition by-products often generate gases which can form pinholes, cracks and craters in the protective coatings. These defects can be detrimental to coating properties including aesthetics, heat resistance and corrosion resistance and typically limit the coating thickness to less than about 100 microns.
  • a higher-film-build generally allows complete deposition of the powders on a substrate and once cured, it increases the protective coating's barrier of protection.
  • powder-based coating compositions which are capable of providing heat-resistant protective coatings which may have a film thickness greater than about 100 microns, are substantially free of coating defects, and display improved high temperature durability.
  • thermoforming powder coating composition comprising a ceramic additive for use on metal substrates including steel, aluminum, iron and the like.
  • Ceramic additives include inorganic oxide and/or metal.
  • the presence of the inorganic oxide and/or metal additive to the starting composition has extended the time and the temperature to which the composition may be subjected without thermal degradation, either at low film thickness, and particularly when making high film thickness coatings, that is coatings with a thickness greater than about 60 or more preferably greater than about 80, or still more preferably greater than about 100 microns in thickness.
  • the additive can improve the heat resistance of a powder coating composition by at least about 20%. The heat resistance is measured by the tape pull test.
  • the improvement in heat resistance can be manifested either as the ability to maintain integrity at higher temperatures for a set period of time, or the ability to maintain integrity at a set temperature for longer time periods.
  • This composition further provides abrasion resistance and electrical resistance. It can be particularly useful for coating high temperature stacks, mufflers, manifolds, boilers, ovens, furnaces, steam lines, heat exchangers, barbecue equipment, cooking utensils and other parts that require a high heat resistance powder coating compositions.
  • the heat resistant polymeric coating compositions of the present invention can be coated onto a substrate which displays 0% Crosshatch adhesion failure after 2 hours at 540°C, said coating comprising: a) the reaction product of: i) glycidyl-functional polyacrylic polymer; and a ii) hydroxyl-functional polysiloxane; and b) at least one inorganic oxide particle or metal particle.
  • One aspect of the invention is directed to a heat resistant coating composition
  • a heat resistant coating composition comprising : a) at least one glycidyl-functional polyacrylic polymer; b) at least one hydroxyl-functional polysiloxane; c) at least one inorganic compound selected from the group consisting of silicates, hydrates of silicates, metasilicates and mixtures thereof; d) at least one ceramic material selected from the group consisting of a metal oxide, a metal and mixtures thereof; and
  • the coating composition can be heated to form a continuous film having a thickness greater than about 45 microns.
  • the coating formed has good thermal resistance at temperatures of from about 370°C to about 540°C, based on the tape pull test, depending on the thickness of the film.
  • the present invention is further directed to heat resistant protective coating compositions comprising : a) at least one glycidyl-functional polyacrylic polymer; b) at least one hydroxyl-functional polysiloxane; c) at least one inorganic compound which is not an inorganic oxide; d) an inorganic oxide or metal or mixture of inorganic oxide and metal; and e) an optional flow control agent, wherein said composition can be heated to form a continuous film having a thickness greater than about 45.
  • the at least one inorganic compound can be silicates, hydrates of silicates, metasilicates and mixtures thereof. These coatings have excellent heat resistant characteristics and pass the tape pull test after about 4 and 24 hours at temperatures up to about 530°C (about 1000°F) as compared to the compositions without component d additives, which displayed good thermal endurance to temperatures of about 340°C to about 395°C after about 4 and 24 hours.
  • the present invention is also directed to articles comprising at least one substrate, and present on at least one surface of the substrate is a composition comprising: a) the reaction product of: i) at least one glycidyl-functional polyacrylic polymer; and ii) at least one hydroxyl-functional polysiloxane; b) of at least one inorganic compound which is not an inorganic oxide; c) at least one inorganic oxide or metal; and d) at least one optional adhesion promoter.
  • the invention discloses a method for the preparation of heat resistant protective coatings comprising the steps of: a) providing a dry blend of powder-based materials comprising: i) at least one glycidyl-functional polyacrylic polymer; ii) at least one hydroxyl-functional polysiloxane; iii) at least one inorganic compound which is not an inorganic oxide; iv) at least one inorganic oxide or metal (including mixtures of inorganic oxides and metals); and v) an optional flow control agent, b) melt mixing said blend and cooling to form solid particulate; c) grinding said particulate to form a powder-based composition wherein said composition comprises an average particle size less than aboutl50 microns; and d) coating said composition on a substrate and heating to a temperature greater than about 190°C or greater than about 205°C.
  • an adhesion promoter can also be present in the coating composition.
  • the protective coatings of the present invention are characterized as having increased heat resistance properties and are substantially free of coating defects, especially at high film thickness.
  • the coatings are particularly useful on articles which are subjected to elevated temperatures including stacks, mufflers, manifolds, boilers, ovens, furnaces, steam lines, heat exchangers, barbecue equipment and cooking utensils. Furthermore, a benefit of being able to apply this coating at a high film build is to accommodate the variety of geometrical shapes of different articles and to allow for variations in manual spraying of the powder coating composition. These coatings exhibit substantially no pitting.
  • compositions of the present invention comprise a silicone resin, in a range from about 5.0% ⁇ by weight to about 40.0% by weight, and preferably from about 10.0% by weight to about 30.0% by weight, based on the total composition solids.
  • the silicone resin can be any alkyl and/or aryl substituted polysiloxane, copolymer, blend or mixture thereof, the alkyl substitution preferably selected from alkyl groups of 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and most preferably methyl, propyl and the aryl substitution most preferably comprising phenyl groups.
  • the silicone resins are heat stable, preferably they do not decompose up to at least 316°C (600°F) when exposed for 90 hours. More preferably they will not decompose when subjected to ambient environmental conditions (e.g., in the presence of air) at 343°C (650°F) for two weeks.
  • silicone resins useful in the practice of the present invention comprise silicone polymers, such as those prepared from organochlorosilanes (such as methyltrichlorosilane, phenyltrichlorosilane and dimethylchlorosilane), and commercially available materials such as phenylsilicone Silres ® 601 or methylsilicone MK, available from Wacker Silicone, Adrien, ML), and proplyphenyl Z-6018 or methylphenylsilicone 6-2230 available from Dow Corning, etc.
  • Suitable resins are also described in U.S. patent Nos. 3,585,065, 4,107,148, 3,170,890 and 4,879,344, incorporated herein by reference.
  • a hydroxyl-functional polysiloxane is used, with the hydroxyl- functionality up to about 10% by weight, preferably in a range from about 0.5% by weight to about 10.0% by weight, more preferably from about 1.0% by weight to about 15.0% by weight, and most preferably from about 5% to about 15% by weight based on the total polysiloxane solids.
  • the compositions may include hydroxyl-functional organo-siloxanes, said organo-siloxane comprises units, including dimethyl, diphenyl, methyl-phenyl, phenylpropyl and their mixtures.
  • hydroxyl-functional polysiloxanes examples include Dow Corning ® 1-0543, Dow Corning ® 6-2230 and Dow Corning ® Z-6018 from Dow Corning (Midland, MI); Wacker Silres ® MK and Wacker Silres ® 601 from Wacker Silicone Corp., (Adrien, MI); General Electric SR-355 from General Electric (Waterford, NY); and PDS-9931 from Gelest, Inc., (Tullytown, PA).
  • Other suitable silicone-based polymers include those described in U.S. Patent No. 4,107,148 (Fujiyoshi et al.) and U.S. Patent No. 4,879,344 (Woo et al.), incorporated herein by reference. Said polymers can self-condense and/or react with glycidyl functional polymers to form a crosslinked network.
  • Acrylic polymers are also present in the powder-based compositions, and they are preferably glycidyl-functional polyacrylic polymers. These glycidyl functional acrylic resins act as curing agents. Suitable resins include at least about 5 wt-% to about 100 wt-% glycidyl functionality. These curing agents aid in the curing of the powder coating composition and also, can substantially reduce the condensation reaction which has troubled the prior art. Examples of commercially available glycidyl-functional polyacrylic polymers include Fine-Clad TM A-244A from Reichold Chemicals, Inc. (Research Triangle Park, NC), and Almatex PD-7690 from Anderson Development Company (Adrain, MI).
  • Said polymers may react with hydroxyl-functional compounds, through an addition mechanism, to form a crosslinked network.
  • a glycidyl-functional acrylic resin is present in an amount effective to allow curing and substantially reduce the condensation of the reaction, preferably in a range from about 1.0% by weight to about 20.0% by weight, and preferably from about 3.0% by weight to about 15.0%) by weight, based on the total composition solids.
  • the reaction between the hydroxyl functional resin and the glycidyl functional curing agent is an addition reaction; however, there may be some amount of condensation that occurs between silanol groups which can be tolerated. It will be understood by one of skill in the art that the more glycidyl-functionality in the acrylic resin, the less condensation occurs.
  • Inorganic compounds are present in the powder-based compositions in a range from about 10.0% by weight to about 70.0% by weight, and preferably from about 20.0% by weight to about 40.0% by weight, based on the total composition solids.
  • the preferred inorganic compounds are hydrated silicates of aluminum (mica), calcium metasilicate (wollastonite) and their mixtures.
  • Commercially available pigments include Micro Mica ® C-3000 from KMG Minerals (King Mountain, NC) and Nyad ® 325 from Nyco (Willsboro, NY). It is surmised that the inventive coating unique heat resistant properties can be attributed, in-part, to said compounds. For example, it is known that inorganic compounds are often used as fillers to increase the coatings volume and economics.
  • mica and wollastonite significantly increase the coating heat resistance properties.
  • Inorganic fillers such as zinc oxide, zinc borate, barium sulfate, calcium sulfate, calcium carbonate, hydrated silicate of magnesium and anhydrous sodium potassium alumina silicate fail to increase the coatings heat resistance properties.
  • mica and wollastonite enhance the glycidyl-silanol addition reaction to form a substantially crosslinked network.
  • these inorganic compounds are especially needed for white coatings. These inorganic compounds preferably have average particle sizes of from about 5-100 microns, more preferably 5-60 microns and most preferably 5-40 microns.
  • the preferred materials of this class include, but are not limited to, inorganic oxides such as aluminum oxide, titanium oxide, chromium oxide, zirconium oxide, cesium oxide, magnesium oxide, iron oxide, mixed oxides (e.g., BaO/TiO 2 , CaO/SiO 2 , 2CaO/SiO 2 , CaO/TiO 2 , MgO/TiO 2 , 2SiO 2 /3Al 2 O 3 ., etc.
  • Other inorganic oxides include tin oxides, nickel oxides, barium oxide, lead oxide, copper oxides, magnesium oxide and the like, especially inorganic oxides which can fuse or coalesce at temperatures above 425°C or above 480°C to form ceramic materials.
  • Metals which are preferred in the practice of this invention are the metals which may be used to form the inorganic oxides listed above, particularly those metals whose oxides form ceramics when heated above 425°C or 480°C (such as aluminum, zirconium, chrome, titanium and the like). This preference for these metals may be indicative of a reaction of the metals with oxygen present in the system (e.g., bound oxygen) to form a fused or bound metal oxide link to the hydroxyl-functional siloxane or other inorganic oxides or silicates within the system or to the substrate.
  • oxygen present in the system e.g., bound oxygen
  • the inventors are not bound by this hypothesis, but gratuitously offer it as a possible suggestion for a basis of selecting metals for the practice of this aspect of the present invention.
  • inorganic oxides Mixtures of inorganic oxides, mixtures of metals and mixtures of inorganic oxides and metals may be used in the practice of the present invention, and the concentration of these materials within the powder-based coating composition may range from about 1%, 10% or 20% by weight in the powder-based coating composition up to about 50%), 60% or 70% by weight in the powder-based coating composition.
  • a preferred concentration in the practice of the present composition may be about 4% by weight to about 45% by weight or about 8% by weight to about 40%) by weight of the total composition.
  • the metals and/or inorganic oxides are preferably added as particulate materials, usually of a size range between about 0.05 to about 100 microns, more preferably between about 0.05 and about 50 microns, and still more preferably between about 0.1 and about 10 microns.
  • the ceramic materials can increase the heat resistant temperature of a powder coating composition by at least about 20%, more preferably by at least about 30%). This improvement is evident at low film thickness as well as high film thickness.
  • Flow control agents optionally can be present in the powder-based compositions in a range from 0% to from about 0.2% by weight to about 3.0% by weight, and preferably from about 0.5% by weight to about 1.5% by weight, based on the total composition solids.
  • the flow control agents may include acrylics, silicones and fluorine- based polymers.
  • Examples of commercially available flow control agents include Resiflow P-67 9 and Clearflow Z-340 8 from Estron Chemical, Inc. (Calvert City, KY); Mondaflow 7 2000 from Monsanto (St. Louis, MO); Modarez 7 MFP from Synthron, Inc. (Morgantown, NC); and BYK 7 361 from BYK Chemie (Wallingford, CT). Said agents enhance the compositions melt-flow characteristics and help eliminate surface defects.
  • the powder-based compositions may contain additives including adhesion promoters, degassing agents, catalysts, fillers, texturizers, coloring agents, plasticizers, surfactants and their mixtures.
  • adhesion promoters can be used in the powder-based compositions including epoxy-based polymers, silane-based polymers, phenolic resins, chlorinated polyolefins and their mixtures. Examples of commercially available adhesion promoters include Araldite 7 GT-7013 and Araldite 7 GT-7220 from Ciba-Geigy co oration (Hawthorn, NY).
  • the adhesion promoters may be present as 0% by weight or in a range from about 0.1% ⁇ by weight to about 20.0%) by weight, and preferably from about 0.1% by weight to about 15.0% by weight, based on the total composition solids. It has been found in the practice of the present invention that such materials as boron carbide (B 4 C), boron nitride, Cr 3 C 2 (chromium carbide), CrSi 2 , HfB 2 , HfC, Hf Si 2 , MoSi 2 , NbC, CaF 2 ,.LiF, TiC, LiCl, MgF 2 , Si 3 N 4 , and the like can provide good additional properties to the composition and the coating.
  • B 4 C boron carbide
  • Cr 3 C 2 chromium carbide
  • Degassing agents can be used in the powder-based compositions and may be present as 0%> by weight or in a range from about 0.1% by weight to about 5.0% by weight, and preferably from about 0.5% by weight to about 3.0%> by weight, based on the total composition (e.g., solids).
  • Examples of commercially available degassing agents include Uraflow B from GCA Chemical Corporation (Brandenton, FL), Oxymelt A-2 8 from Estron Chemical (Calvert City, KY), and Benzoin from Generichem Corp. (Little Falls, NJ). Said materials assist in the release of gases during the curing process.
  • catalysts may be used in the powder-based compositions which may include stannous octoate, dibutyl tin dilaurate, zinc octoate and their mixtures.
  • Commercially available catalysts include Octaflow ST-70 8 from Estron Chemical, Inc., (Calvert City, KY) and Actiron DBT 8 from Synthron (Morgantown, NC).
  • the catalysts may be present in a range from about 0.01% by weight to about 5.0% by weight, and preferably from about 0.1 % by weight to about 3.0%) by weight, based on the total composition solids.
  • the catalysts are used to enhance the curing characteristics of the powder-based compositions.
  • inorganic fillers can be used in combination with the preferred inorganic compounds of the present invention. Suitable examples include zinc oxide, magnesium silicate (Talc), calcium sulfate, barium sulfate, zinc borate, anhydrous sodium potassium alumino silicate, calcium sulfate, calcium carbonate and their mixtures.
  • a commercially available filler is Duramite 7 from ECC International (Atlanta, GA).
  • the fillers may be present in a range from about 10.0%> by weight to about 50.0%> by weight, and preferably from about 20.0% by weight to about 40.0% by weight, based on the total composition solids.
  • the fillers can be used to provide texture, control gloss and increase the coatings volume to enhance its economics.
  • texturizers can be used in the powder-based compositions and include polytetrafluoroethylene, rubber, glass grit, talc and their mixtures.
  • a commercially available texturizer includes Shamrock SST-3 from Shamrock Technologies (Newark, NJ).
  • the texturizer may be present in a range from about 1.0% by weight to about 10.0%> by weight, and preferably from about 2.0% by weight to about 7.0% by weight, based on the total composition solids.
  • Coloring agents can be used in the powder-based compositions and any heat stable coloring agent may be used.
  • the preferred coloring agents are carbon black and black mixed metal oxides.
  • Commercially available coloring agents include Black No. 101 from the Shepard Color Company (Cincinnati, OH), and Special Black 100 from Degussa AG (Frankfurt, Germany).
  • the coloring agent may be present in a range from about 1.0%) by weight to about 25.0% by weight, and preferably from about 5.0% by weight to about 15.0%) by weight, based on the total composition solids.
  • the adhesion promoter is present from about 0.01 ) by weight to about 10%) by weight of the polymer content of the composition, more preferably from about 0.5%) by weight to about 5% by weight, most preferably from about 1%> by weight to 5%> by weight, to increase initial adhesion and reduce cross-hatch adhesion failure to less than 5%>.
  • Cross-hatch adhesion failure is tested by scoring a grid of 5 x 5 lines spaced about 2mm apart, applying an acrylate pressure sensitive adhesive tape on a polyester backing against the crosshatching, and quickly removing the tape by pulling at an angle of about 90 degrees. The number of squares of coating which have been removed are then measured.
  • a polymeric additive By reducing the cross-hatch adhesion failure (after melting and curing of the silicone resin composition) to less than 5%>, a polymeric additive is identified as an adhesion promoter. It has been surprising in the practice of the present invention that typical polymeric additives conventionally used as adhesion promoters (e.g., bisphenol A epoxy resins, Novolac-modified bisphenol A, resols, polyethylene, polypropylene, silane resins, phenolic resins with chlorinated polyolefins and polyethylene terephthalate) did not perform according to the present definition of adhesion promoters or adhesion enhancers.
  • typical polymeric additives conventionally used as adhesion promoters e.g., bisphenol A epoxy resins, Novolac-modified bisphenol A, resols, polyethylene, polypropylene, silane resins, phenolic resins with chlorinated polyolefins and polyethylene terephthalate
  • adhesion promoters of the present invention are, as previously noted, determinable by the test procedures described below.
  • the preferred chemical classes of adhesion promoters comprise (meth)acrylic polymers and copolymers, including ambifunctional or polyfunctional (meth)acrylic polymers and copolymers, as homogeneous or heterogeneous compositions, blends, mixtures or melts.
  • (meth)acrylic is used to encompass both acrylic and methacrylic resins.
  • Acrylate polymers (including copolymers) derived from acrylic acid, methacrylic acid, acrylic anhydride, n-butyl acrylate, n-butyl methacrylate, methyl acrylic acid, methyl methacrylic acid, isobutyl acrylic acid, isobornyl (meth)acrylate, decyl acrylate, lauryl (me h)acrylate, trimethylsilyl(meth)acrylate, methacryloxypropyltrimethoxysilane, fluorinated acrylates (such as those described in U.S. patent No. 5,397,669) and the like are most preferred.
  • Copolymers of these (meth)acrylates, or blends or mixtures of (meth)acrylates as with olefinic resins e.g., polyethylene and polypropylene
  • vinyl ethers butyl vinyl ether, propyl vinyl ether, etc.
  • vinyl esters e.g., vinyl acetate
  • styrenes e.g., 4-methylstyrene, styrene, alpha-methylstyrene
  • the more preferred promoters comprise methacrylic or acrylic acid (anhydrides or alkylacrylic acid) copolymers with ethylenically unsaturated comonomers, particularly olefinic copolymers (ethylene, propylene, styrene, butadiene, etc.) which, by themselves,
  • TM form linear polymer chains.
  • Ethylene-acrylic acid copolymers such as Primacor 5990 Polymer are the most preferred.
  • High cure temperatures are normally needed for curing to produce coatings with improved initial adhesion. Temperatures of at least 280°C, and as high as 550°C are usually employed. Even at these high curing temperatures, some prior coatings still do not have cross-hatch failures of less than 5%. It is therefore surprising that coating compositions of the present invention can be cured at temperatures of less than about 230°C, substantially lower than normally used, to produce coatings having cross-hatch failures of less than 5%, through the incorporation of adhesion promoters.
  • Plasticizers may be used in the present invention to provide flexibility.
  • Plasticizers may include polymeric resins, elastomers, waxes, oils and their mixtures.
  • the plasticizers may be present in a range from about 1.0% by weight to about 15.0% by weight, and preferably from about 5.0%> by weight to about 10.0%> by weight, based on the total composition solids.
  • Surfactants can be used and may include inorganic polyphosphates, organic polyacids, nonionic block copolymers and their mixtures.
  • the surfactants may be present in a range from about 0.5% by weight to about 3.0%) by weight, and preferably from about 1.0% by weight to about 2.0%) by weight, based on the total composition solids.
  • the surfactants are useful as dispersing agents for the inorganic compounds and inorganic fillers.
  • Fluidizing agents can be used to improve the dry-flow characteristics of the powder-based compositions. Examples include fumed silica, alumina oxides and their mixtures.
  • the fluidizing agent can be present in a range from about 0.05% by weight to about 1.0% by weight, and preferably from about 0.1% by weight to about 0.5%) by weight, based on the total composition solids.
  • the powder-based materials are combined and agitated to form a dry blend.
  • the blend is melt mixed in an extruder, at a temperature less than about 130°C, and cooled to form solid particulate.
  • Fluidizing agents may be added at this stage of the process to enhance the materials dry-flow characteristics.
  • the particulate is ground at a temperature less than about 20°C. Lower temperatures reduce melt coagulation and enhance the grinding process.
  • the powder-based compositions can have an average particle size in a range from about 0.1 microns to about 500 microns and preferably from about 30 microns to about 200 microns.
  • Said compositions may be applied on a substrate through electrostatically spraying or with a fluidized bed method.
  • the coated substrate is then heated to a temperature in a range from about 180°C to about 250°C, and preferably from about 190°C to about 240°C, and more preferably from about 200°C to about 225°C.
  • elevated temperatures can accelerate a material's reactivity.
  • a reference describing the frequency of bond formation is described in AOrganic Chemistry.--, T.W. Graham Solomons, second edition, pages 139- 141. Briefly, the collision theory of reaction rates describes how the rates of chemical reactions are directly proportional to the collision frequency. In the present invention, it is surmised elevated temperatures increase the frequency and extent of addition and/or condensation reactions to form a crosslinked polymer matrix.
  • the protective coatings can have a film thickness in a range from about 25 microns to about 255 microns, and preferably from about 45 microns to about 200 microns.
  • a higher-film-build can enhance the coating and increase the protective value of the coatings with a greater film thickness that provides an extra barrier of protection. For example, during manual and automated spraying applications it is often necessary to deposit a high-film-build to assure a complete deposition of the particles on the substrate.
  • a protective coating comprising a film thickness greater than about 100 microns is preferred in that such a high-film-build can enhance the coatings resistance to abrasion and environmental corrosives.
  • the protective coatings provide excellent heat resistant properties and are particularly useful on articles which are subjected to elevated temperatures including stacks, mufflers, manifolds, boilers, ovens furnaces, steam lines, heat exchangers, barbecue equipment and cooking utensils.
  • the tape pull test used to measure heat resistance is described below and was run at 530°C. This is a very severe test and as mentioned before, the samples that passed this test are much preferred, though the ones that failed at 530°C are also included in the present invention if they improve their heat resistances by at least about 20% through the addition of the metal, metal oxides or mixtures thereof.
  • the improvement is at least about 30%>, more preferably at least about 50%.
  • the improvement can be either maintaining integrity at a higher temperature for a set period of time, or at a set temperature for longer amounts of time, with the most desirable being an increase in both temperature and time over compositions without the addition of metal, metal oxides or mixtures thereof.
  • the present invention is further illustrated, but not limited to, the following examples.
  • Aluminum cast coupons were electrostatically sprayed with powder-based compositions and heated in an electric oven for 15 minutes at 204°C.
  • the samples were subjected to a temperature of 530°C (about 1000°F) and tested at about 4 and 24 hours. Other temperatures can be used, as appropriate.
  • the samples were cooled to ambient room temperature and aged for at least one hour.
  • the samples were then covered with a piece of Scotch 7 Brand A8919 ⁇ tape from 3M Company (St. Paul, MN) and firmly applied using hand pressure.
  • the tape was quickly removed, using a 90° peel mode, and visually inspected for signs of coating failure.
  • the protective coating passes the TPTM when said coating is not transferred to the tape.
  • Dow Corning 1-0543 Resin is a silicone comprising a mixture of Dimethyl-, Diphenyl-, Methyl-, and Phenyl- Silicone moieties.
  • A-244-A(GMA) is a glycidyl functional (meth)acrylic polymer
  • Z-6018 is a silicone resin having a mixture of Phenyl- and Propyl- Silicone moieties,
  • P-67 is an Acrylic Polymer/Silicon resin mixture
  • Uraflow B is Benzoyl Phenyl Carbinol ST-70 is a Stannous Octoate
  • SST-3 is a Polytetrafluoroethylene
  • NYAD 325 is Calcium Metasilicate
  • Aluminum 1663 is a dedusted Aluminum Flake ZrO 2 is Zirconium Oxide
  • Boron Carbide is boron carbide
  • compositions of the examples are tabulated in Table I below and the results of Pull-Tape Test tabulation in Table II. They are made in the conventional manner for powder coating. TABLE I

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  • Engineering & Computer Science (AREA)
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Abstract

L'invention concerne un procédé relatif à l'élaboration de revêtements de protection résistant à la chaleur, qui consiste à traiter des compositions en poudre à des températures supérieures à environ 190° C de manière à former des revêtements à haut degré de pelliculage et sensiblement dépourvus de défauts de revêtement. Le type de composition considéré comprend un polymère polyacrylique (de préférence un polymère polyacrylique à groupe fonctionnel glycidyle), un polysiloxane à substitution hydroxyle et un métal ou un oxyde métallique, et de préférence un composé inorganique qui n'est ni un métal ni un oxyde métallique (par exemple, silicate).
PCT/US1999/000197 1998-01-06 1999-01-06 Composition de revetement en poudre Ceased WO1999035195A1 (fr)

Priority Applications (1)

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AU21057/99A AU2105799A (en) 1998-01-06 1999-01-06 Powder coating composition

Applications Claiming Priority (2)

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US345598A 1998-01-06 1998-01-06
US09/003,455 1998-01-06

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001081466A1 (fr) * 2000-04-20 2001-11-01 Dsm N.V. Composition de resine durcissable, film durci et produit composite
EP1316592A1 (fr) * 2001-11-30 2003-06-04 Solutia Austria GmbH Additifs pour des peintures pulvérulentes
EP1403350A1 (fr) * 2002-09-25 2004-03-31 Rohm And Haas Company Revêtement en poudre stable à la chaleur avec finition ridée en surface
US6897259B1 (en) 2002-09-25 2005-05-24 Rohm And Haas Company Heat stable wrinkle finish powder coatings
CN107674582A (zh) * 2017-10-19 2018-02-09 广东捷宇粉体涂料有限公司 一种耐候型耐明火灼烧的粉末涂料及其制备工艺

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997022728A2 (fr) * 1995-12-04 1997-06-26 H.B. Fuller Company Procede de preparation de revetements protecteurs ameliores

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997022728A2 (fr) * 1995-12-04 1997-06-26 H.B. Fuller Company Procede de preparation de revetements protecteurs ameliores

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001081466A1 (fr) * 2000-04-20 2001-11-01 Dsm N.V. Composition de resine durcissable, film durci et produit composite
US7122253B2 (en) 2000-04-20 2006-10-17 Dsm N.V. Curable resin composition, cured film, and composite product
KR100759652B1 (ko) * 2000-04-20 2007-09-17 디에스엠 아이피 어셋츠 비.브이. 경화성 수지 조성물, 경화막 및 복합 생성물
KR100761184B1 (ko) * 2000-04-20 2007-10-04 디에스엠 아이피 어셋츠 비.브이. 경화성 수지 조성물, 경화 필름 및 복합 제품
EP1316592A1 (fr) * 2001-11-30 2003-06-04 Solutia Austria GmbH Additifs pour des peintures pulvérulentes
EP1403350A1 (fr) * 2002-09-25 2004-03-31 Rohm And Haas Company Revêtement en poudre stable à la chaleur avec finition ridée en surface
US6897259B1 (en) 2002-09-25 2005-05-24 Rohm And Haas Company Heat stable wrinkle finish powder coatings
CN107674582A (zh) * 2017-10-19 2018-02-09 广东捷宇粉体涂料有限公司 一种耐候型耐明火灼烧的粉末涂料及其制备工艺

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